Pseudorabies virus (PRV) is a disease which infects many species of animals worldwide. PRV infections are variously called infectious Bulbar paralysis, Aujeszky's disease, and mad itch. Infections are known in important domestic animals such as swine, cattle, dogs, cats, sheep, rats and mink. The host range is very broad and includes most mammals and, experimentally at least, many kinds of birds (for a detailed list of hosts, see D. P. Gustafson, "Pseudorabies", in Diseases of Swine, 5th ed. , A. D. Leman et al. , eds., (1981)). For most infected animals the disease is fatal. Adult swine and possibly rats, however, are not killed by the disease and are therefore carriers.
Populations of swine are particularly susceptible to PRV. Although the adult swine rarely show symptoms or die from the disease, piglets become acutely ill when infected and death usually ensues in 24 to 48 hours often without specific clinical signs (T. C. Jones and R. D. Hunt, Veterinary Pathology, 5th ed., Lea & Febiger (1983)).
PRV vaccines have been produced by a variety of techniques and vaccination in endemic areas of Europe has been practiced for more than 15 years. Losses have been reduced by vaccination, but vaccination has maintained the virus in the environment. No vaccine has been produced that will prevent infection. Vaccinated animals that are exposed to virulent virus survive the infection and then shed more virulent virus. Vaccinated animals may therefore harbor a latent infection that can flare up again. (See, D. P. Gustafson, supra).
Live attenuated and inactivated vaccines for PRV are available commercially in the United States and have been approved by the USDA (See, C. E. Aronson, ed., Veterinary Pharmaceuticals & Biologicals, (1983)).
Because adult swine are carriers of PRV, many states have instituted screening programs to detect infected animals. DNA/DNA hybridization can be used to diagnose actively infected animals utilizing the DNA sequence of the instant invention. Some of the PRV glycoproteins of the present invention are also useful in producing diagnostics for PRV infections and also to produce vaccines against PRV.
PRV is a herpesvirus. The herpesviruses generally are among the most complex of animal viruses. Their genomes encode at least 50 virus specific proteins and contain upwards of 150,000 nucleotides. Among the most immunologically reactive proteins of herpesviruses are the glycoproteins found, among other places, in virion membranes and the membranes of infected cells. The literature on PRV glycoproteins refers to at least four viral glycoproteins (T. Ben-Porat and A. S. Kaplan, Virology, 41, pp. 265-73 (1970); A. S. Kaplan and T. Ben-Porat, Proc. Natl. Acad. Sci. USA, 66, pp. 799-806 (1970)).